Ventilation Circuit Gas Timing for Anesthesia Safety
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Solution Overview
Problem
Existing ventilation systems for artificially ventilating patients during anesthesia may not ensure sufficient operational safety, particularly when rapidly increasing the volume flow of anesthetic or oxygen mixtures, which can lead to a bolus and endanger the patient.
Innovation Solution
The ventilation system is configured to ensure that the additional gas mixture, containing anesthetics or oxygen, reaches the feed point only during expiration or intermediate phases, not during inspiration phases, thereby preventing a sudden influx of high concentrations of anesthetics or oxygen into the patient's lungs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the volume flow of additional gas mixture is rapidly increased to ensure sufficient anesthesia depth, then the anesthesia effect is improved, but the risk of bolus formation increases which endangers the patient
Solution Approach 1:
The control unit predicts the propagation duration before the additional gas mixture reaches the patient, and delays the start of expelling the gas mixture until the predicted arrival time corresponds to an expiration phase. This preliminary timing action prevents bolus formation during inspiration while still allowing rapid volume flow increases when needed.
Solution Approach 2:
The ventilation system operates with periodic inspiration and expiration phases. The control unit synchronizes the delivery of additional gas mixture with these periodic phases, specifically timing it to arrive during expiration phases when the patient is not inhaling, thereby converting a potentially harmful continuous flow into a safe periodic delivery pattern.
2Productivity
If the volume flow of additional gas mixture is rapidly increased to respond to changing anesthesia requirements, then the responsiveness is improved, but anesthetic waste increases due to bolus formation
Solution Approach 1:
The control unit performs preliminary calculation of propagation duration based on target volume flow and circuit characteristics, then delays the actual gas mixture delivery by this predicted time. This preliminary timing optimization ensures the gas arrives during expiration phases, preventing bolus waste while maintaining rapid responsiveness to anesthesia requirements.
Solution Approach 2:
The system continuously monitors ventilation parameters and adjusts the timing and volume flow of additional gas mixture delivery based on real-time feedback. The control unit recalculates propagation duration as volume flow changes, creating a closed-loop system that optimizes anesthetic delivery efficiency and minimizes waste.
3Loss of time
If the additional gas mixture is delivered immediately upon request to ensure rapid response, then the response time is improved, but the precision of timing control deteriorates leading to potential bolus events
Solution Approach 1:
The control unit calculates the propagation duration in advance based on the target volume flow and ventilation circuit characteristics before actual gas mixture delivery begins. This preliminary timing calculation enables precise scheduling of gas delivery to ensure arrival during expiration phases, resolving the conflict between rapid response and timing precision.
Solution Approach 2:
The system replaces intuitive immediate-response mechanical delivery with a computationally controlled timing system. The control unit uses algorithms to predict gas mixture arrival times and adjusts delivery timing accordingly, substituting precise electronic control for simpler but less precise immediate mechanical response.
Data Source
AI summary
A ventilation arrangement (200) and process ventilate a patient (P) with a ventilation circuit (40) connecting a ventilator (1) to a patient-side coupling unit (21). The ventilator performs a sequence of ventilation strokes, including expelling a quantity of a gas mixture that flows in the ventilation circuit to the patient-side coupling unit. Gas mixture exhaled by the patient flows in the ventilation circuit from the patient-side coupling unit to the ventilator. A gas mixture supply unit (31, 48) expels an additional gas mixture into the ventilation circuit at a feed point (38). A specification sets a volume flow of the additional gas mixture. In response to capturing a specification, a propagation duration for the expelled additional gas mixture to reach the feed point is predicted. The additional gas mixture is controlled to ensure that the expelled additional gas mixture reaches the feed point in an expiration phase.